Apple just announced the iPhones 5S featuring the A7 SoC, which is the world's first consumer ARM based SoC with 64-bit support. We're likely talking about an updated version of Apple's Swift microprocessor with ARMv8 support.

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It isn't a datapath thing. Currently, any precision math, or long hash work/encryption (common for apps using data) require 2 or 4 clocks to handle, which means higher consumption and lower performance. 64 bit registers means that drops to a theoretical 1/2 of power and clocks used to process. Which is a massive increase in throughput. Yes, most apps do not take advantage of this, but they will if they are apps that tend to eat CPU time.Reply

64 means you can use 64 bit registers and arguments for instructions, typically per clock, so code that uses 64 arguments can be run faster, rather than spliting high precision / length instructions into two steps. This is especially good for reducing time spend on memory transactions, which means low power ram can be used, retaining high efficiency with improved performance. Plus this allows for virtualization (ARMs implementation) which can in turn mean sandboxing apps. Most apps may be natively written with 16 / 32 in mind, but using 64 does not necessarily mean they need to use loads of ram, using 16 megs of ram, with 64 bit registers can still yield performance boosts. This is essentially *doubling* the available resources / performance of the pipeline.Reply

64 bit doesn't double de performance.Let say you add 1 + 1. It will be just as fast on 8, 16, 32 or 64 bits.If you need integers (not floating point) numbers higher than 4 billion, then 64 bit is faster. If you only use these numbers in 0.01% of you calculation, then you get a speed boost 0.01% of the time.They doubled the number of registers, which will improve performance (less transfers to RAM), but has nothing to do with 64 bit.Reply

You do know that people use computers as something more than glorified calculators, right? Not all computing is "numeric," it involves other data types, like strings, and other operations, like logical comparisons.Reply

Logical comparisons aren't faster on 64 bit. Only you can compare larger numbers at the same time. Branching isn't faster on 64 bit.Strings do not really benefit from 64 bit either. They are array of bytes. Where is the benefit of 64 bit? Reply

My 32 BIT CRC run almost 2X faster when converted to 64 BIT. String copies and encryption run almost 2X faster (with no code changes) run almost 2X faster. Long word optimized string searches can also run faster in many cases by not doing simply "byte" wise operations.Reply

Are the people who are implying 64-bit implies an automatic performance increase talking about x86? x86-64 is a weird case because you get twice the registers in long mode on an AMD64 CPU, which increases performance. That's not the case with other architectures, in fact outside of certain very specific usage cases (big scary scientific data processing) and the need to address more RAM - the performance difference is nil, or even worse a decrease due to shuffling about twice as much data... I can vouch for 32-bit userland being faster on the whole on UltraSPARC and PPC64 - I don't see why that wouldn't be the case on ARM unless there's something I don't know about the architecture.

But Apple have always been big on the marketing - they know 64-bit is useless on mobile... Of course the new architecture is very interesting for different reasons others have outlined here, but '64 bit' sounds impressive when you're faintly aware that previous mobile phones had 'less bits', no? Just like it did when Nintendo were marketing the N64....Reply

The amusing thing here is that you're giving a case for 64 bit to be slower. Look at how the numbers are fully represented:

0x00000000000000000000000000000001

Vs

0x0000000000000000000000000000000000000000000000000000000000000001

For data paths of equal length, the 32 bit chip would be able to move more packets of data even though the throughput in raw GB/s would be the same.

Purely going to 64 bit has two main advantages: more addressable memory and fast 64 bit integer computation. When ARM and x86have gone 64 bit the architecture changed more than the size of the general purpose registers.Reply